Cushion mounting in punch press

ABSTRACT

A machine press bed assembly including an air cushion seated in the press bed, air input means integral with the press bed floor, aperture means in an end wall of the cushion accommodating said air input means, and holddown means penetrating the press bed sides engaging the cushion, the cushion being removable from said press bed by disengaging the holddown means.

United States Patent 1 3,580,558

[72] Inventors Robert A. Helrigel [56] References Cited t f u D It Rod kK UNITED STATES PATENTS 2 417 794 3 1947 Werner 267/1(l9) Ward; Harry E.Kelthley, Hastings, Mich. {21] p No. 789,868 3,451,667 6/1969 Anderson267/1 (30, [22] Filed Jan. 8, 1969 Primary ExaminerJames B. Marbert [45]Patented May 25, 1971 Attorney-Meyer, Tilberry and Body [73] Assignee E.W. Bliss Company Canton, Ohio ABSTRACT: A machine press bed assemblyincluding an air [54] CUSHION MOUNTING 1N PUNCH PRESS cushion seated inthe press bed, air input ,means integral with 4clmms6nmwmg Figs the,press bed floor, aperture means in an end wall of the [52] US. Cl267/119 cushion accommodating said air input means, and holddown [51]Int. Cl Fl6k 9/31 means penetrating the press bed sides engaging thecushion, [50] Field of Search 267/130, the cushion being removable fromsaid press bed by disengagl 19, 75 ing the holddow'nmeans.

RY W

l I l 20 88 9690 76 89 Patented May 25; 1971 3 Sheets-Sheet 5 FE 1 mmCUSHION MOUNTING IN PUNCH PRESS DESCRIPTION The present inventionrelates to improvements in a machine press, and more particularly to anovel means for assembly and disassembly of an air cushion and press bedcombination.

Air cushions of the type to which the present invention is directed aretermed inverted C-type cushions, and comprisea lower, inner air pistonand an upper, outer cylinder, the piston being in the form of an innersleeve having a lower end wall which seats on the press bed floor; theupper cylinder being in the form of an outer sleeve which telescopicallyand reciprocally slides over the inner piston sleeve, having an upperend wall or working surface. The piston and cylinder are held in anextended relationship by a cushion of air between the opposed end walls.The invention will be described with particular reference to this typeof cushion, although it will be appreciated that the invention hasbroader application with cushions of other types.

One advantage of the inverted C-type cushion is that the upper cylinder,being on top, encompasses the lower piston and prevents chips and dirtfrom getting between the piston and cylinder sleeves scoring the wallsof the same. Dirt may collect on the piston, but it is wiped down in thecushion downstroke.

Although air cushions are used with different types of presses, fordifferent press operations, a typical press using air cushions is a drawpress. In order to contain the air cushion or cushions, the press bed isprovided with a bed floor and upstanding sides, the air cushion beingseated on the floor and encompassed by the bed sides. Depending upon thesize of the press, several cushions may be employed in a side-by-siderelationship within the press bed. A press bolster then seats on top ofthe press bed sides and the air cushion working surface or upper endwall acts on components of the press dies which penetrate the bolster.These components under the force of the cushion working surface or endwall provide substantially uniform pressure on all parts of the blank orworkpiece during the drawing operation.

It is apparent that because of the function which the air cushionsserve, they must occupy substantially the full space encompassed by thebed sides, and in particular the air cushion working surface or end wallmust .extend substantially completely across this space. The result isthat clearances between the bed sides and the cushion, particularly theupper working surfaces thereof, will be small.

In addition, the cylinder or upper sleeve often is guided in its up anddown motion by internal guide strips on the press bed sides, so that forthis reason as well, clearances between the cylinder or upper sleeve andthe press bed sides will be small.

Assembly of an air cushion to a press bed requires two steps oroperations which heretofore have caused substantial problems. It is arelatively simple matter to drop or position an air cushion within thebed, but then the cushion must be secured to the bed, and the pressurechamber of the cushion must be connected to a source of air. The limitedclearance between the cushion and the bed sides has made it difficult toarrive at a satisfactory solution to the assembly problem, and inparticular, to a satisfactory means for securing the cushion to the bedand connecting the cushion to a source of air.

The reason why it is important to secure the air cushion to the pressbed, particularly in the case of a cushion of the inverted C-type, isthat the upper cylinder reciprocates rapidly under the force of the diecomponents, with substantial inertia, causing the .cushion on the upwardstroke to jump upwardly on the bed floor. This is bad for reasons whichwill become apparent, but in addition, it is important that the cushionsbe accurately centered or positioned in the press bed, and thismotionot' the cushions makes it difficult to maintain the desiredcentering or positioning.

It is known to bolt the air cushion to the press bed floor from beneaththe press bed, the bolts extending upwardly through the bed floor andengaging the piston member. One problem is that in order to have accessto the bolts, it is necessary to excavate a pit beneath the press, oralternatively provide a means for'tipping the press to obtain access tothe underside thereof. The use of a pit clearly is employed in the caseof larger presses. Whereas these were satisfactory solutions some yearsago, high labor costs now make it prohibitive to use either-recourse.

it also has been proposed to use a plurality of upstanding dowelspositioned in the press bed floor, cooperating with holes in the bottomof the piston member end wall to locate the latter in the press bed, butpermitting the cushion to be lifted readily from the bed. This proposalhas proven unsatisfactory, since the upward forces of the cushion uppercylinder, on upward stroking of the press slide, still cause the pistonmember to jump up and down on the bed floor, shaving and wearing thedowels, ultimately causing them to break. After the dowels have worn,wear also begins to occur on guide strips for the upper cylinder, andscoring of the cylinder and piston sleeves can also occur.

In a rapid cycling press, up to cycles per minute, the life time fordowels clearly is short.

The seriousness of thisproblem'is such that manufacturers have gone tothe extent of suggesting that operation or use of the press be modifiedto overcome the problem. The highest velocity of the press slide occursat the slide up or down midstroke, and pressure is usually released fromthe air cushion at about the midupward stroke. To obtain release of thecushion at a point of lesser velocity, and reduce the intensity of thecushion movement, manufacturers have suggested adjustment of the pressslide so that the pressure is released at about onethird stroke, butthis clearly restricts versatility of the press.

It has also been proposed to cut holes in the press bed sides tofacilitate assembly or removal of the cushion from the press bed, or tovary dowel design, but in all instances, the solutions have been eitherexpensive or unsatisfactory.

Part of the problem of easy assembly of an air cushion to the press bedis the need to connect and disconnect air hoses with the cushionchamber. It is apparent that standard connections will interfere withease of removal of the cushion, partly because of limited access betweenthe cushion and press bed sides, and partly because of the timegenerally required for connecting and disconnecting conventionalcouplings.

To avoid the use of conventional couplings, an air connector has beenemployed seated on and part of the press bed floor, the air cushionpiston being provided with an aperture which receives the air connector.The end wall of the air cushion piston slides over the air connector,the latter being connected with a source of air. This solution, however,has proved unsatisfactory since the up-and-down motion of the aircushion piston member on the locating dowels wears the air connector,and any packing seals between the connector and cushion piston end wall.This in turn results in air leakage and ultimately, after substantialwear of the dowels, in wearing of the air connector itself.

In accordance with the present invention, the above disadvantages areovercome by providing in a machine press which comprises a press bedincluding a floor and upstanding bed sides defining inner and outersurfaces, an air cushion including a lower piston member and an uppercylinder member, the lower piston member comprising an end wall seatedon the press bed floor, the upper cylinder member being telescopicallyand reciprocally received on said piston member and including an upperend wall, wherein the clearance between the cylinder member and pressbed sides is small, the cylinder member and piston member combining todefine a cushion chamber for compressing a fluid between said end walls,which fluid biases the cylinder member upward; the improvementcomprising in combination fluid input means seated on the press bedfloor integral therewith, aperture means in the piston member end wallto accommodate said fluid input meansfpacking means sealing saidaperture means in the spacebetween said fluid input means and saidpiston member end wall, said piston member further defining peripheraloutwardly extending flange means adjacent the press bed sides; andholddown means penetrating the press bed sides from the outer surfaceinwardly engaging said flange means.

For purposes of this application, the fluid input means is integral withthe press bed floor in the sense that it is bolted, welded or otherwisesubstantially permanently affixed to the floor.

It is a primary object of the present invention to provide a means forassembly and disassembly of an air cushion and a press bed by which thecushion is securely anchored within the bed, but is easily disassembledfrom the bed,

It is further an object of the present invention to provide a means forsecuring an air cushion to a press bed by which wearing of parts orsurfaces is prevented, but which does not unduly interfere with assemblyand disassembly of the cushion and the bed.

The invention, and the advantages thereof, will become apparent uponconsideration of the following specification, with reference to theaccompanying drawings, in which FIG. 1 is a perspective view of a pressassembly in accordance with the invention;

FIG. 2 is a section view taken along lines 2-2 of FIG. 1;

FIG. 3 is a top view of a press assembly bed and air cushion assembly inaccordance with the invention;

FIG. 4 is a section view taken along line 4-4 of FIG. 3',

FIG. 5 is a perspective partially broken away view of an air cushion andpress bed in accordance with the invention; and

FIG. 6 is an enlarged view of an air connector in accordance with theinvention.

Referring now to the drawings, wherein the showings are for the purposeofillustrating the preferred embodiment of the invention 'only and notfor the purpose of limiting the same, the figures show a press A whichhas a press bed B, the bed B including upstanding sides C which containa pair of air cushion assemblies D (FlGS. 25). The design of the pressand its use of air cushions is well known in the press art, as is theuse of cushions in other types of presses, and further discussion of thepress itself is not necessary, except with regard to the assembly anddisassembly of the air cushion from the press bed in accordance with thepresent invention.

Turning to the drawings in detail, the press includes a frame 10comprising vertically extending frame sides 12 and 14, the press bed Bincluding, between the sides, front and rear upstanding walls 16 and 18(of shorter height than the press sides) which will hereinafter bereferred to as the bed sides.

Between the bed sides 16 and 18 and frame sidewalls, the bed is providedwith a lower floor 20 (FIGS, 2-5), the bed sides and frame wallsdefining a pair of bed cavities 22 and 24 separated by an upstandingdividing wall 26 which extends between the sides 16 and 18. Each of thebed cavities is sized to house an air cushion D.

As shown in FIG. 2, the press bed sides 16 and 18 are comprised oflongitudinally extending flanges or blocks 28 and 30, seated on thepress bed floor 20, along the side edges thereof, and upstanding heavyflat plate members or ribs 32 and 34 secured to the upper surfaces 36and 38 of the flanges. These components of the press bed preferably areall welded together to provide an integral unit.

Each air cushion D comprises a lower cylindrical piston member 40 (FIG.2) including a cylindrical sleeve 42 and a lower end wall 44 which seatson the floor 20 of the press bed, between the press bed flanges 28 and30. The sleeve includes an outer cylindrical bearing surface 46terminating in a lower annular abutment surface 48. Defined by thesleeve 42 is an upwardly facing large opening 49.

Reciprocally and telescopically received on the lower piston member 40and sleeve 42 is a movable cylinder member 50 including an upper, outer,cyli-ndricalsleeve 52 and an upperflat end wall 54, the latter defininga working surface 55. The upper sleeve 52 is provided with an innercylindrical bearing surface 56 which slidingly'engages the bearingsurface 46 ofthe piston member, and at the free lower annular edge 57 ofthe upper sleeve 52, the sleeve is provided with an annular stop 58bolted to the sleeve and protruding inwardly from the bearing surface 56to engage the abutment surface 48 of the piston member. This preventsupward withdrawal of the cylinder member 50 from the piston member 40,the upper cylinder member and lower piston member combining to define aninternal cushion chamber 60 between the end walls 44 and 54 of the twomembers.

In a manner to be described, the chamber is pressurized with a suitablefluid, the pressure biasing the cylinder upwardly and being maintainedby means of an O-ring seal 62 seated in the upper outer edge 63 of thepiston member sleeve 42 between the piston member and the inner bearingsurface 56 of the upper sleeve 52.

The type air cushion shown is a pneumatic inverted C-type cushioncharacterized in that the cylinder member is on top and the pistonmember below. The main advantage with this type cushion is that it isrelatively free of contamination, since with the cylinder on top, chipsand dirt cannot get between the piston and cylinder and score thebearing surfaces of the two members. Dirt may collect on the piston, butmeans not shown can be provided for wiping down the piston on thecushion downstroke.

On top of the press bed sides 16 and 18 it is conventional practice toposition a press bolster, a large heavy plate member to which the pressdies are attached. The cushion working surface 55 is spaced slightlybelow the bolster lower surface (when the cushion is fully extended),the working surface engaging components of the dies which penetrate thepress bolster. The purpose of the cushion is to maintain a substantiallyconstant force on the die components and thereby on the blank beingformed. Because of this function, it is apparent that the workingsurface at least must substantially completely occupy the space betweenthe bed sides as shown, and the clearance between the bed sides and theend wall 54 of the cylinder will be minimal.

Not shown are guides or guideways for movement of the cylinder member50. Although the type of guiding utilized is not part of this invention,if the cylinder is externally guided with guideways on the inner sidesof the press bed, for this reason as well the clearance between thepress bed sides and the cushion will be minimal, and inadequate toobtain access to the inside of the press bed or into the press bedcavity once the cushion has been placed in the bed cavity.

Because the cushion is of the inverted C-type, it also is evident thatit must be preassembled before being placed in the press bed, i.e., thecushion cylinder must be slipped over the cushion piston and loweredsufficiently below the piston abutment surface 48 to attach the stop 58to the cylinder.

These two conditions, minimal access to the press bed cavity and noaccess to the cushion chamber, make it impossible to bolt the cushion tothe bed floor from the upper side downwardly; i.e., either through thepiston end wall 44, or from the inside of the bed cavity.

In accordance with the present invention, the cushion is secured to thepress bed by means of a plurality of holddown pins 66 positioned atspaced intervals along the press bed sides (Notice FIG. 3, in which fourholddown pins are shown along each side of the press bed.). The holddownpins penetrate the press bed sides at about 45, and for this purpose,holes 68 are drilled through the flanges 28 and 30 of the press bedsides starting at about the outer junction point of the flanges 28 and30 with the ribs 32 and 34, angled inwardly and downwardly to enter thebed cavity at a point slightly above the press bed floor. The holes arethreaded to receive the holddown pins, which also are threaded, and tolock the holddown pins once threaded into place, they are provided withlocknuts 70 bearing against angled surfaces 72 of wedged-shaped members74 welded between the upper surfaces 36 and 38 of the flange members andthe press bed ribs 32 and 34.

The air cushion piston-end wall 44 is-extended beyond thecircumferencedefinedby piston'sleeve 4250 as to define arectangularflange .76 occupying substantially the full floor area ofeach press bed cavity. On opposite sides,.adjacent the sides 16 and 18of the press bed, the flange 76is provided with opposed sloped flangesurfaces 78 and 80 against which the holddown pins bear. Thisarrangement holds the cushion securely in place, and in operation, nodifficulty has been experienced with the piston jumping up-and-down onthe press bed.

Adjacent the rear side 18 of the press bed, secured to the bed floor 20,is an air connector 82 comprised of a U-shaped hollow block member 84having an end face 86 which is seated in a circular depression 88 in theupper surface of the press bed floor, the depression being sufficientlyshallow so that the connector extends above the elevation of the bedfloor. The press bed is drilled from the outside inwardly with ahorizontal channel 89 which is in flow communication with a verticallyextending drilled passageway 90 drilled downwardly into the bed floor. Acentered opening 92 in the air connector block communicates with thevertically extending passageway 90. At the outward exposed end of thehorizontal channel 89, a suitable valve nipple 94 is secured, adapted tobe attached to a source of air.

Details on the air connector are shown in FIG. 6.

The air connector 82 is bolted to the press bed floor by means of aplurality of annularly spaced bolts 96, and it thereby becomes asubstantially permanent or integral part of the bed. The cushion pistonis provided with an aperture 98 in the end wall 44 thereof which alignswith the air connector, so that when the cushion is placed in the bedcavity and the piston end wall seats against the bed floor, the end wallpasses over the air connector, the latter having a height sufficient sothat it extends completely through the end wall, and has an exposedouter peripheral edge 102. This edge is chamfered, so that when thepiston member is lowered on to the press floor, it slides into positionon the chamfered edge.

The inside wall of the aperture 98 in the piston end wall 44 is machinedto define an annular seat 104 containing an O- ring packing 106.Preferably, the packing has two upstanding flaring opposed lips 108 and110 which bear against the opposed surfaces of the piston member endwall and air connector block to provide a pressure seal against thesetwo surfaces. This prevents air from escaping in the space between theair connector and the piston member end wall. In addition, the airconnector block is provided in its seated face with an annular groove112 containing an O-ring seal 114 making the connection between the bedand air connector airtight.

It should now be apparent that the air connector and holddown pins ofthe invention cooperate to provide a novel means for assembly anddisassembly of an air cushion in a press bed, which means overcomes thedisadvantages of prior means of assembly. In particular the inventionprovides a means for securely holding the cushion in the press bed, onewhich does not interfere with connection or disconnection of thecushion. When it is desired to assemble an air cushion in the press bedcavity, it is a simple matter to lower the cushion into the cavity, overthe air connector, and to turn the holddown pins, the latter securingthe cushion to the extent that shaving and wear of the connector doesnot occur. To expand the cushion assembly, it is not necessary toconnect air lines. To remove the air cushion, it is a simple matter toreverse the holddown pins, and withdraw the cushion from the bed cavity.By virtue of the holddown pins, use of the air connector becomesfeasible both for assembly and disassembly of the cushion and bed. Ifthe press were held in place by means of dowels, the up-and-downmovement of the piston member on the press bed would quickly wear thepacking 106, causing leakage between the air connector and piston memberend wall.

It is apparent that the advantages of the invention are achieved withoutthe need of a pit beneath the press for access to the underside of thepress bed, or without the need of a means for tipping the press.

it is further apparent that the means for assembly and disassembly ofthe air cushion and press bed in accordance with the present inventionavoids the costs, time, and maintenance problems of the prior art.

Although the invention has been described with reference to specificembodiments, variations within the scope of the following claims will beapparent to those skilled in the art.

What we claim is:

1. A press assembly comprising a press bed including a floor andupstanding bed sides;

a lower piston including an end wall on said press bed floor and anupstanding cylindrical sleeve;

an upper cylinder including an end wall and a downwardly extendingsleeve telescopically and reciprocally received on said piston sleeve,the clearance between said upper cylinder and press bed sides beingsmall;

said piston and upper cylinder combining to define a cushion chamber forcompressing a fluid between the end walls thereof; fluid input meansintegral with the press bed floor compris ing a block member extendingabove the floor and passageway means in communication with a source ofair;

aperture means in the end wall of said piston to accommodate said fluidinput means; and

holddown pin means to hold said piston to the press floor,

said holddown pin means comprising a plurality of pins penetrating thesides of said press bed and engaging surfaces of said air cushionpiston.

2. A press assembly comprising:

a press bed including a floor and upstanding bed sides;

a lower piston including an end wall on said press bed floor and anupstanding cylindrical sleeve;

an upper cylinder including an end wall and a downwardly extendingsleeve telescopically and reciprocally received on said piston sleeve,the clearance between said upper cylinder and press bed sides beingsmall;

said piston and upper cylinder combining to define a cushion chamber forcompressing a fluid between the end walls thereof; fluid input meansintegral with the press bed floor comprising a block member extendingabove the floor and passageway means in communication with a source ofair;

aperture means in the end wall of said piston to accommodate said fluidinput means; and

holddown pin means to hold said piston to the press bed floor, saidholddown pin means comprising a plurality of pins penetrating the sidesof said press bed and engaging surfaces of said air cushion piston;

said piston end wall comprising flange surfaces extending outwardlybeyond the circumference of the piston sleeve, said pin means engagingsaid flange surfaces.

3. The assembly of claim 2 wherein said press bed sides comprise flangemeans seated on opposed front and rear edges of the press bed floor,upstanding ribs seated on said flange means, said pin means extendingdownwardly and inwardly through said flange means from the upper surfaceof the flange means to an elevation slightly spaced from the press bedfloor to engage said piston flange surfaces.

4. The press assembly of claim 2 wherein the press bed sides are in thefront and back of the press, said piston end wall flange surfaces beingadjacent the press bed sides, comprising at least two pins engaging eachof the end wall flange surfaces.

1. A press assembly comprising a press bed including a floor andupstanding bed sides; a lower piston including an end wall on said pressbed floor and an upstanding cylindrical sleeve; an upper cylinderincluding an end wall and a downwardly extending sleeve telescopicallyand reciprocally received on said piston sleeve, the clearance betweensaid upper cylinder and press bed sides being small; said piston andupper cylinder combining to define a cushion chamber for compressing afluid between the end walls thereof; fluid input means integral with thepress bed floor comprising a block member extending above the floor andpassageway means in communication with a source of air; aperture meansin the end wall of said piston to accommodate said fluid input means;and holddown pin means to hold said piston to the press floor, saidholddown pin means comprising a plurality of pins penetrating the sidesof said press bed and engaging surfaces of said air cushion piston.
 2. Apress assembly comprising: a press bed including a floor and upstandingbed sides; a lower piston including an end wall on said press bed floorand an upstanding cylindrical sleeve; an upper cylinder including an endwall and a downwardly extending sleeve telescopically and reciprocallyreceived on said piston sleeve, the clearance between said uppercylinder and press bed sides being small; said piston and upper cylindercombining to define a cushion chamber for compressing a fluid betweenthe end walls thereof; fluid input means integral with the press bedfloor comprising a block member extending above the floor and passagewaymeans in communication with a source of air; aperture means in the endwall of said piston to accommodate said fluid input means; aNd holddownpin means to hold said piston to the press bed floor, said holddown pinmeans comprising a plurality of pins penetrating the sides of said pressbed and engaging surfaces of said air cushion piston; said piston endwall comprising flange surfaces extending outwardly beyond thecircumference of the piston sleeve, said pin means engaging said flangesurfaces.
 3. The assembly of claim 2 wherein said press bed sidescomprise flange means seated on opposed front and rear edges of thepress bed floor, upstanding ribs seated on said flange means, said pinmeans extending downwardly and inwardly through said flange means fromthe upper surface of the flange means to an elevation slightly spacedfrom the press bed floor to engage said piston flange surfaces.
 4. Thepress assembly of claim 2 wherein the press bed sides are in the frontand back of the press, said piston end wall flange surfaces beingadjacent the press bed sides, comprising at least two pins engaging eachof the end wall flange surfaces.